This invention is related to the following U.S. patent applications, assigned to the same assignee as the instant application and all having a filing date of Aug. 30, 1985, which by reference are incorporated herein, Ser. Nos.: 771,431; 771,443; 771,322; 771,432; 771,433; 772,280; 771,329; 771,442; 771,397; 772,061; 771,380; 771,459; and 771,545.
1. BACKGROUND OF THE INVENTION
This invention relates to multi-wheel vehicles and in particular to controllable multi-wheel vehicles and still more particular to controllable multiple wheel vehicles having a fail braking system.
In an operation where a controllable mobile robot is able to navigate across a factory floor under the control of a navigation system, it is desirable to quickly bring the mobile apparatus to a halt in the event of loss of power or a requirement for stopping. The technique that is used with manual controlled mobile apparatus is a dead man brake in which the mechanical brakes will not engage the wheels as long as a button is pressed, but the moment the button is released, then the mechanical brakes bring the vehicle to a stop. However, with automation quickly taking over factories and mobile robots serving the purposes of material handlers then in the event of loss of power to the navigation system or to the mobile apparatus it is necessary to bring the mobile apparatus to a fail safe stop when a dead man breaking system is not available.
2. SUMMARY OF THE INVENTION
A controllable mobile apparatus such as a mobile robot travels to a commanded destination under the control of a guidance system that provides speed and direction commands to the controllable mobile apparatus. A plurality of wheels carry the mobile apparatus to the commanded position in response to the speed commands from the guidance system. Steering commands will cause the selected members of the plurality of wheels to vary their angles by a predetermined amount in response to the steering commands that are provided by the guidance system. Additionally, a braking system is provided for stopping the controllable mobile apparatus when it encounters loss of power or communications with the guidance system.
The braking system is used in conjunction with the servo motors that are used for steering the mobile apparatus and includes a storage device such as a capacitor which stores up power under non-braking conditions. A transfer device, such as a relay, will transfer the power from the capacitor to the servo motors that are used to steer the mobile apparatus and is connected in such a means to uncoordinate the steering wheels and to cause them to turn in a direction that opposes the forward motion of the mobile apparatus.
These and other advantages and objectives of the invention will be apparent from reading of the specification in conjunctions with the figures in which: